The art of analytical chemistry has been greatly advanced since biochemistry began emerging as a primary scientific frontier, requiring increasingly sophisticated analytical methods and tools to solve problems. Likewise the medical profession has lent impetus to the growth of analytical chemistry, with its desiderata of both high precision and speed in obtaining results.
To satisfy the needs of the medical profession as well as other expanding technologies, such as the brewing industry, chemical manufacturing, etc., a myriad of analytical procedures, compositions and apparatus have evolved, including the so called "dip- and-read" type reagent test devices. Reagent strip test devices enjoy wide use in many analytical applications, especially in the chemical analysis of biological fluids, because of their relatively low cost, ease of usability, and speed in obtaining results. In medicine, for example, numerous physiological functions can be monitored merely by dipping a reagent strip test device into a sample of body fluid, such as urine or blood, and observing a detectable response, such as a change in color or a change in the amount of light reflected from or absorbed by the test device.
Many of the "dip-and-read" test devices for detecting body fluid components are capable of making quantitative or at least semiquantitative measurements. Thus, by measuring the response after a predetermined time, an analyst can obtain not only a positive indication of the presence of a particular constituent in a test sample, but also an estimate of how much of the constitutent is present. Such test devices provide the physician with a facile diagnostic tool as well as the ability to gage the extent of disease or of bodily malfunction.
Illustrative of such test devices currently in use are products available from the Ames Division of Miles Laboratories, Inc. under the trademarks CLINISTIX, MULTISTIX, KETOSTIX, N-MULTISTIX, DIASTIX, DEXTROSTIX, and others. Test devices such as these usually comprise one or more carrier matrixes, such as absorbent paper, having incorporated therein a particular reagent or reactant system which manifests a detectable response, e.g., a color change in the presence of a specific test sample component or constituent. Depending on the reactant system incorporated with a particular matrix, these test devices can detect the presence of glucose, ketone bodies, bilirubin, urobilinogen, occult blood, nitrite, and other substances. A specific change in the intensity of color observed within a specific time range after contacting the test device with a sample is indicative of the presence of a particular constituent and/or its concentration in the sample. Some of these test devices and their reagent systems are set forth in U.S. Pat. Nos. 3,123,443; 3,212,855; 3,814,668; etc.
Regardless of whether the test device is used for the determination of a biological fluid or the analysis of a commercial or industrial fluid, the normal procedure requires that the test device be blotted after contacting the sample or specimen to be tested in order to remove excess fluid from the test device matrix prior to visual or instrumental analysis. The blotting procedure must be done extremely carefully to avoid interference with the reaction occuring in the test device matrix. Ideally, the blotting procedure is performed uniformly each time a test device is used in order to achieve consistent results. The blotting procedure becomes very critical when instruments such as reflectance photometers are used to determine a detectable response. Current analyzers require that inoculated test devices be manually blotted prior to their insertion into such analyzers. In accordance with the present invention, manual blotting is eliminated and a test device can simply be inoculated and presented for analysis.